Low-complexity and low-latency implementation of the Godard/CMA update

This paper discusses methods for calculating and implementing the update error term for the popular blind equalization algorithm known as Godard´s (1980) algorithm, or the constant modulus algorithm (CMA), without the use of multipliers so that chip area and signal latency are both substantially reduced. One approach uses a decision-directed CMA update term, and another uses region-based quantization. The quantized error term can be calculated using a look-up table in place of costly multipliers and adders. Baseband and passband implementations are discussed, and computer simulations verify our methods